63. 〃 The Living Animal increases in Size by adding to the Substances which compose its Body, like Substances; these, however, are chiefly derived directly from other Animals or from Plants 90
64. 〃 The living Animal, after it has grown up, detaches part of its Substance, which has the Power of growing into a similar Animal, as an Egg 91
65. 〃 Living Bodies differ from Mineral Bodies in their Essential Composition, in the manner of their Growth, and in the fact that they are reproduced by Germs 91
67. 〃 The order of Mental Phenomena: Psychology 93
All the time that we are awake we are learning by means of our =senses= something about the world in which we live and of which we form a part; we are constantly aware of feeling, or hearing, or smelling, and, unless we happen to be in the dark, of seeing; at intervals we taste. We call the information thus obtained =sensation=.
When we have any of these sensations we commonly say that we feel, or hear, or smell, or see, or taste, something. A certain scent makes us say we smell onions; a certain flavour, that we taste apples; a certain sound, that we hear a carriage; a certain appearance before our eyes, that we see a tree; and we call that which we thus perceive by the aid of our senses a =thing= or an =object=.
Moreover, we say of all these things, or objects, that they are the =causes= of the sensations in question, and that the sensations are the =effects= of these causes. For example, if we hear a certain sound, we say it is caused by a carriage going along the road, or that it is the effect, or the consequence, of a carriage passing along. If there is a strong smell of burning, we believe it to be the effect of something on fire, and look about anxiously for the cause of the smell. If we see a tree, we believe that there is a thing or object, which is the cause of that appearance in our field of view.
In the case of the smell of burning, when we find on looking about, that something actually is on fire, we say indifferently either that we have found out the cause of the smell, or that we know the =reason why= we perceive that smell; or that we have =explained= it. So that to know the reason why of anything, or to explain it, is to know the cause of it. But that which is the cause of one thing is the effect of another. Thus, suppose we find some smouldering straw to be the cause of the smell of burning, we immediately ask what set it on fire, or what is the cause of its burning? Perhaps we find that a lighted lucifer match has been thrown into the straw, and then we say that the lighted match was the cause of the fire. But a lucifer match would not be in that place unless some person had put it there. That is to say, the presence of the lucifer match is an effect produced by somebody as cause. So we ask why did any one put the match there? Was it done carelessly, or did the person who put it there intend to do so? And if so, what was his motive, or the cause which led him to do such a thing? And what was the reason for his having such a motive? It is plain that there is no end to the questions, one arising out of the other, that might be asked in this fashion.